The present invention related to an amplifier architecture, and more particularly, to an amplifier circuit having a stacked main amplifier and a parallel sub-amplifier to achieve low power, high gain, and low noise.
Amplifiers are common circuit components implemented in a variety of fields. Taking a wireless communication device for example, a low noise amplifier (LNA) is commonly used in an RF receiver for amplifying signals received from an antenna. If the wireless communication device is a portable device, a low power structure is demanded. However, the conventional low noise amplifier has high power consumption to achieve the desired power gain. Therefore, it is desired to provide a novel amplifier circuit with low power, high gain, and low noise to meet the design requirements for a portable apparatus.